Process of hardening and toughening armor-plates.



3o respective high temperatures wili very with to the high temperature which permits an EMIL sunnusnmienn, or

' Poconos or Museums men.

BECIFIGATION forming part of Letters "A lies-mum April 21, l$96. s

121 all whom r't-may concern: Be it known that-1, Emn Eunnnsnonoun, a subject of the King of Prussia,'Emperor of Germeny, and a resident of Essen in the King: g done i Pruss'o, German Empire, have inroute new on v useful Improvements in Pruecones of Hardening and Toughening Armor Flutes, of which the following is a full, clear, and erect description. v to The method or process forming the subjectv of the present invention has for its object'the lmprovement'of steei armor-plates by imparting to the side thereof which is exposed to the impact projectiles the greatest suitable r5 hurdness -end to theother side thereof the greatest toughness which the owner plate 'meterieljcuu acquire. By such construction and the mode of manufacture hereinafter described is obtained the greatest resistance to ac cracking and the highest degree'of strength. After steel armor pistes have been improved in ,quality by being suddenly cooled down from a high temperature that renders the molecules capable of an easy rearrange- 2 5' went they may be made to acquire the qual-o ity of extreme toughness by being heated a second time to a lower temperature than the first heating and by being allowed to cool slowly down from said temperature. Thesethe nature and composition of the steel, and hence directions cannot be given in exact degrees of temperature; but the first heating should be of such liigh'degree us will permit 3 5 eesyfiow or rearrengement of the molecules, and this may be obtained by heating up to about, soy, 800 to 1,000" centi rude, but should stop short of the melting-point; but in order thetthe armor-plate shell'combine 4o. the most efficient degree of hardness of one side and the greatest degree of toughness of the other side I treat the plate in the followiug manner: The plate is first im raved in quality by beiug'heoied, as'above esorihed,

esey or, ready flow or rearrangement of the I molecules, end the entire plate is then and "den'ly cooled from such temperature byimmersion or spraying in the usual manner. I

call thiethe alitydmproviug heat. By v this means th steel acquires not only con rrsu STATEs a GERMANY, AssIeNon moirRIsufKRUPP, or SAM-E PLACE.

muonsmesnsiou PLAT-ss. Batent menses, Madonna 19, 1900. allelic-588E135 rutheniu .siderable hardness, butelsoan extreme fineness of grain or texture which makes it cape;- I ble of subsequently acquiring the greatest degree of toughness; notes the hardness is now too great to allow of machining or shoping' the plate the tempershould be then drawn audthe plate be then. mechi'uedor shaped as may be desired, or the plate is heated to a temperature at which hardening will not take place; and the'plete is then cooled suddenly from this temperature. Then the platecan be machined or shaped while cold; This heat I coil the tempering heat. The plate having been thus properly worked, one side' viz., the side intended to be exposed-to the impacooi projectiles-is heated to a temperature adapted to produce the requireddegree of hardness. This I call the -hardening heat, and the other or rear side is heated toa 7o temperature below that to which the exposed side is heated. This letter temperatureshould be such as to produce toughnessinthe 3 highest degree and will be a red heat. This I call the toughening heat. The plate is thensuddenly cooled either by immersion or spraying.

The heating of the two sides is. preferably efiected for practical reasons at one and'the same time by bringing these parts which ere to be more intensely heated rapidly to the said higher temperature, while those partswhich are not to be heated so intensely are either embedded in send or placed upon a rather cool hesrth, and thus withdrawn from the direst or full action of the furnace, or they may 7 be placed on a, hollow frame and kept at the suitable lower temperature by meausof cool-V ing-geses introduced into such hollow frame, or, less practically butproductive oi the some result, the more intense heating of the surface to be hardened and the sudden cooling thereof may be caused to. follow on or 'it may precede-the heating of the other side to the lower temperature and the sudden cooling thereof. 7 It will be understood that. this process is suitable for armor-plates of homogeneous steel and alloys of steak-such as chrome-steel, Wolfram steel, nickel steel, chrome-nickel 10:. steel, &c. --as well as for cemen ted,compound, and other plates. In the case of cemented if the-operation was such, as to impart the- 7 employed in the subsequent treatment which" does "not exceed the temperature-of the tem their parts arediiie'rently heated.

gla'tes the first e dispensedwith, because the heating necessary for the cementing process may beutil- 'ized at the same time for the operation of im-I proving the grain or texture. Moreover, in

essary for the shaping and machining opora-' tions and which 'rsiuterposed I between: the quality-improving heat and the hardening and toughening heat, (which heats are'of ditferent temperatu res,) may be dispensed with, because {the shaping of the plates may in such case be efljected previously thereto; but

if this tempering heat has been eflt'ected and required maximum toughness to the back of the plate any desired; temperature may be peringh'eat; I s v a -In conclusionit may be statedthat the herein-described operation-which precedes the actually novel part of the process-that is'to say, the first. operation for the purpose" of-improving the grain or textureof the ma:-

terial and also the secondoperation. forfaciliqn'ality impro'v'ing heat may desired, heating. the other side which is to become tough. to a temperature lower than that necessary to produce hardening, and suddenly cooling the plate from the different temperatures. 4 a

2. The herein-described process for impart-- ing special hardnessto one side and maximum toughness to the other'side of plates made of steel. or mixtures of steel capable of being hardened, consisting in first subjecting the plate't'o a high temperature permitting an easy molecular rearrangement,-then suddenly 'cooling' the plate,then heating the side which isv to be hardenedto a temperaturecorrespending to the d'egree'of hardnessdesired,

:while heatingthe other side, which-is tobecome tough, to a lower heat, andbelow that necessaryto produce hardening, and then suddenly cooling the plate from the diff temperatures. r 1 1 '3. The nerern-uescrr bed process for mpart-- ing special hardness toone-side and maximum toughness to the other side of. plates made ot'steel or mixtures of steel, capable of being hardened, c'onsistingfin first subj'e'ctiu g the plate to a high temperature permitting aneasy molecular rearrangement, then suddenly cooling) the plate, then-heating the plate to a] low-heat, not highenough to produce hardening,-then suddenly or, slowly'cooling and tating the-machining and shaping of the' material m aybe, replaced-hy-similar or. e u v lent treatments without altering the essential.

natureof the process.- For instan rye-,the plates to be hardened on one side only may have imparted to them a suitable grain or texture by beingrolled at a low temperature before,

\V-hat I claim as new isthedilferenttemperatures; 1 .-,,In testimony whereof I have signed my 1. The herein-described process forimpai't- I ing special hardness to one side and inaxi l,

mum" toughness to the other sideof plates. made of steel or mixtn res of steel capable ofi being, hardened, consisting in heatingthe side which is to 'be hardened to atemperature corresponding to'the degregefihardness;

shapingtne .plnte ater coo l1ng; thenreheat ingthe side of the plate which istobe hardened tola. temperature.corresponding to the degree of hardness desired, while heating the other side,"which is to become tough, to a red heat below that necessary to produce harden ing, andfthenfsuddenly cooling theplatc from name to this specification in the presence of two subscribing witnesses. I j I MI n i-iRENsBnRcER.

Witnesses f f WILLIAM EssENu-tmx,

- Fni;'rz ARTHOWEYR, t 

